Topic
Circular polarization
About: Circular polarization is a research topic. Over the lifetime, 15201 publications have been published within this topic receiving 234418 citations.
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TL;DR: The circular Bragg phenomenon is the almost total reflection of the incident light of the co-handed circular-polarization state but very little reflection of a cross-handed LPA.
Abstract: Exhibited by structurally chiral materials—such as Reusch piles, cholesteric liquid crystals (CLCs), and chiral sculptured thin films (STFs)—due to their helical nonhomogeneity along a fixed axis, the circular Bragg phenomenon is the almost total reflection of the incident light of the co-handed circular-polarization state but very little reflection of the incident light of the cross-handed circular-polarization state. Manifesting itself in spectral regimes that depend on the angle of incidence, the structural period, and the relative permittivity dyadic, the phenomenon amounts to the formation of a light pipe that bleeds energy backward under appropriate conditions. Mild dissipation and dispersion do not significantly affect the circular Bragg regime. Every structurally chiral material of sufficient thickness is essentially a circular-polarization-sensitive band-rejection filter. Cascades of these materials with or without structural defects can be used to satisfy complex filtering requirements, such as multiband, narrowband, and ultra-narrowband filtering. A shift in the circular Bragg regime due to infiltration of a chiral STF by a fluid enables optical sensing. Sources of circularly polarized light can be fabricated by embedding emission sources in CLCs and chiral STFs.
105 citations
TL;DR: In this paper, the basic radiative transfer coefficients for polarized synchrotron radiation and apply them to the standard jet model for relativistic radio jets are presented, which can successfully explain the unusual circular and linear polarization of the Galactic Centre radio source Sgr A* and its sibling M 81*, and also can account for the circular polarization found in more luminous quasars and X-ray binaries.
Abstract: In inhomogeneous optically thick synchrotron sources a substantial part of the electron population at low energies can be hidden by self-absorption and overpowered by high energy electrons in optically thin emission. These invisible electrons produce Faraday rotation and conversion, leaving their footprints in the linear and circular polarized radiation of the source. An important factor is also the magnetic field structure, which can be characterized in most cases by a global magnetic field and a turbulent component. We present the basic radiative transfer coefficients for polarized synchrotron radiation and apply them to the standard jet model for relativistic radio jets. The model can successfully explain the unusual circular and linear polarization of the Galactic Centre radio source Sgr A* and its sibling M 81*. It also can account for the circular polarization found in jets of more luminous quasars and X-ray binaries. The high ratio of circular to linear polarization requires the presence of a significant fraction of hidden matter and low-energy electrons in these jets. The stable handedness of circular polarization requires stable global magnetic field components with non-vanishing magnetic flux along the jet, while the low degree of total polarization implies also a significant turbulent field. The most favoured magnetic field configuration is that of a helix, while a purely toroidal field is unable to produce significant circular polarization. If connected to the magnetosphere of the black hole, the circular polarization and the jet direction determine the magnetic poles of the system which is stable over long periods of time. This may also have implications for possible magnetic field configurations in accretion flows.
105 citations
TL;DR: To achieve production of 129Xe gas at even higher polarization will rely on further optimization of the pumping cell and laser beam geometries in order to mitigate problems associated with temperature gradients that are encountered at high laser power and Rb density.
104 citations
TL;DR: In this article, a numerical study of the polarization properties of the broadband supercontinuum (SC) generated in birefringent photonic crystal fibers (PCFs) is presented.
Abstract: We present a numerical study of the polarization properties of the broadband supercontinuum (SC) generated in birefringent photonic crystal fibers (PCFs). The simulations are based on generalized coupled nonlinear Schrodinger equations with quantum noise taken into account. The simulations illustrate the complicated polarization behavior in the SC spectra and show that the pulse-to-pulse polarization state of SC spectra fluctuates because of vector modulation instability. We investigate the polarization stability and uniformity of SC spectra under several simulation conditions and discuss generation of the SC in birefringent PCFs for applications with various polarization requirements.
104 citations
TL;DR: If the electrons are emitted in single-step, nonresonant coherent processes, rather than stepwise excitation, the centrifugal potential barrier in the atomic Hamiltonian produces this suppression of the cross section.
Abstract: Multiphoton ionization in xenon has been studied with 1064-nm circularly polarized coherent light, producing electrons with energies up to 15 eV. A strong suppression of the cross section is observed for electrons below 4 eV, but not for linearly polarized light at the same intensity. We show that if the electrons are emitted in single-step, nonresonant coherent processes, rather than stepwise excitation, the centrifugal potential barrier in the atomic Hamiltonian produces this suppression.
104 citations